1. Field of the Invention
The present invention relates to a self-centering airbag, and methods for manufacturing and tuning the same. The present invention also relates to restraint systems incorporating self-centering airbags. Particularly, the present invention is directed to airbags that when deployed are centered about a predetermined location.
2. Background of the Invention
Prior passenger safety systems found in vehicles such as automobiles and aircraft have generally been restraint systems of two principal types, seat belts and airbags. Possibly the earliest to be used was the passenger lap belt which was attached to a fixed substructure at each end and was joined over the user""s lap by suitable buckle assemblies. Normally, one of the two pieces making up the belt was of fixed length while the length of the other piece could be adjusted in order that the belt could accommodate users of all sizes. This type of belt was used for many years in automobiles and remains to this day the principal type of restrain system used for passenger safety in private and commercial aircraft.
Later, to further protect against possible injury, the lap belts in automobiles were modified to include a shoulder strap that was attached at a third fixed point to restrain the passenger""s upper torso against forward movement during a crash event. The latest significant protective equipment added to passenger automobiles were passive restraints or airbags. Airbags, which are inflated by compressed gas, are mounted in the automobile steering column and other fixed locations within the automobile, such as the dash board and side panels. In the event of a sudden deceleration, as in a crash event, sensors identify the event and the compressed gas is released to expand the airbags at high speeds in the direction of the passenger to prevent forward movement of the passenger. Airbags have proven generally effective in providing passenger protection especially when used in conjunction with safety belts.
While airbags are now common as passive restraints for passengers in the front seat of an automobile, their use is not equally widespread in trucks, related commercial vehicles or in the rear seats of automobiles. Further, seat mounted airbags have not been used in aircraft for passenger protection, for reasons having to do primarily with aircraft design and use, seat design and seat location. Seats in commercial aircraft, unlike those in land vehicles, are not fixed in a permanent position. For example, the seats are movable to different locations and are removable. In addition, the backs of aircraft seats are not rigidly mounted but, rather, they swing forward and down in a crash event, so they cannot be used to house airbags.
In order to enable the use of airbags in aircraft by providing a restraint system that is not permanent in nature, later designs have used an airbag/safety belt restraint. U.S. Pat. No. 5,984,350 illustrates such a system where the airbag is embedded within the lap belt. This system uses electronics to sense a crash event wherein an airbag embedded in the lap belt is deployed in a direction away from the passenger wearing the lap belt. The lap belt is comprised of first and second parts that are each fixed at one end to the vehicle sub-structure and are connectable one to the other at the other end over the user""s lap. One belt part is preferably of fixed length while the other belt part""s length is preferably adjustable so that the combined lengths of the two belt parts can be changed as required. The airbag is preferably embedded within the belt part of fixed length.
However, due to the wide range of potential passenger sizes, it is not possible to ensure that the airbag embedded within the belt part of fixed length will be centered with respect to the forward facing portion of the passenger""s body when the lap belt is worn. Since airbags are typically symmetrical in shape, it is difficult to design an airbag that, when deployed, will provide optimal or even adequate protection in a crash event to passengers of all sizes. Additionally, in some applications, an airbag is needed that can be fixed to a structure at a point that is located an offset distance from the airbag""s centerline. Therefore, what is needed is a self-centering airbag. A self-centering airbag is an airbag that when deployed, becomes centered about a desired point that is not necessarily the point to which it is fixed.
It is an object of this invention to provide a combined airbag/safety belt restraint system that will protect vehicle passengers of a wide variety of sizes.
It is a further object of this invention to provide an airbag/safety belt particularly suited for use in aircraft and also for use in land vehicles.
It is a further object of this invention to provide an airbag that is self-centering when deployed.
It is a further object of this invention to provide a method for creating a self-centering airbag.
It is a further object of this invention to provide a method for creating an airbag and an airbag/safety belt restraint system wherein the airbag is self centering when deployed.
It is a further object of this invention to provide a method for tuning the deployment of an airbag.
The system, apparatus and methods of this invention relate to self-centering airbags, particularly single-chamber airbags. Sculpturing, which includes forming at least one cutout in the airbag, is used to form an airbag that when deployed, has a centerline that is not necessarily centered about the point at which the airbag is fixed to a structure (the fixation point). The self-centering airbag can be used as part of a restraint system, wherein the self-centering airbag is embedded within a structure such as a safety belt. Because the centerline of the self-centering airbag can be adjusted or tuned, the self-centering airbag does not need to be embedded in the safety belt in a location that, when the safety belt is worn by a passenger, is central with respect to the relevant part of the passenger""s body. The location of the deployed self-centering airbag""s centerline can also be adjusted or tuned by varying the distance between the self-centering airbag centerline and the fixation point, the angle at which the self-centering airbag is attached to a structure, and the method by which the self-centering airbag is folded in preparation for deployment.
While the devices and methods disclosed herein may be, as noted earlier, used in any type of passenger vehicle, it is especially applicable in those situations where two point attachments, such as lap belts, are used as the sole means of protection. These situations include, for example, aircraft and those automotive applications where a rigid structure is generally not available for airbag installation.